You can now use Amazon Simple Queue Service (SQS) for applications that require messages to be processed in a strict sequence and exactly once using First-in, First-out (FIFO) queues. FIFO queues are designed to ensure that the order in which messages are sent and received is strictly preserved and that each message is processed exactly once.

Amazon SQS is a reliable and highly-scalable managed message queue service for storing messages in transit between application components. FIFO queues complement the existing Amazon SQS standard queues, which offer high throughput, best-effort ordering, and at-least-once delivery. FIFO queues have essentially the same features as standard queues, but provide the added benefits of supporting ordering and exactly-once processing. FIFO queues provide additional features that help prevent unintentional duplicates from being sent by message producers or from being received by message consumers. Additionally, message groups allow multiple separate ordered message streams within the same queue.

FIFO queues are limited to 300 transactions per second (TPS) per API action. This means that, without batching, a FIFO queue can support 300 messages per second (300 sends, receives, and deletes per second). With batching of 10 messages per transaction, a FIFO queue can support 3000 messages per second (a standard queue has unlimited throughput).

Amazon SQS FIFO queues are priced at $0.50 per million API requests, with the first 1 million monthly requests free. FIFO queues are now available in the US East (Ohio) and US West (Oregon) regions, with more regions to follow.

Starting today, the price for Amazon SQS standard queues has been reduced by up to 20% to $0.40 per million requests in all regions (including GovCloud), with the first 1 million monthly requests free. See Amazon SQS Pricing for more details.